1. Field of the invention
This invention relates generally to computer-assisted modeling and planning systems and in particular to a computer-assisted human anatomic and physiologic modeling system used to predict outcomes of medical intervention and further to predict changes in physiologic function under various states, stresses and environments and still further to generate data for disease research.
2. Discussion of Prior Art
Presently physicians use various types of static images of patient anatomical structures when planning medical intervention including drug therapy, interventions, and surgery. Typically these images are derived from magnetic resonance (MR), computed tomography (CT), angiography, or ultrasound data. In addition, the physician will use tests, such as blood pressure, electrocardiograms (EKGs), and cardiovascular function, taken under at least one physiologic state. Since these images are basically two-dimensional static images, the physician must conceptually construct a multi-dimensional image of the location and shape of existing internal anatomic features within the patient. The physician augments the diagnostic data with empirical clinical information in regards to the anticipated outcome for a given class of medical intervention. The physician, based on this diagnostic and empirical data, may estimate anatomic and physiologic outcome of the medical intervention for a specific patient.
A technique has been developed wherein an interactive surgery planning and display system mixes live video of external surfaces of the patient with interactive computer generated models of internal anatomy obtained from medical diagnostic imaging data of the patient. The computer images and the live video are coordinated and displayed to a physician in real-time during surgery allowing the physician to view internal and external structures and the relation between them simultaneously, and adjust his surgery accordingly. In an alternative embodiment, a normal anatomical model is also displayed as a guide in reconstructive surgery. Another embodiment employs three-dimensional viewing.
Another technique employed in localization of internal structures during surgery is known as stereotactic surgery. With this approach, a rigid mechanical frame is attached to the patient before a CT or MR procedure. The frame and its landmarks can be seen in the resulting images. Mechanisms on the frame, position a probe at specific locations within the image.
In a third technique for localization of internal structures using data from different medical imaging modalities, three-dimensional models of anatomy can be created providing images of selected anatomical features and allowing the visualization of internal structure as solid models.
Another technique may be used for predicting, prior to injection, an organ specific contrast enhancement in a patient for a preselected contrast injection protocol for predetermining a computed tomography scan. The technique uses a computer-generated model of human cardiovascular physiology in a hypothetical patient with a specific body habitus subjected to the pre-selected contrast injection protocol. The predicted contrast enhancement may be then used to control a CT scanner or contrast injector system, to perform the injection and scan with the pre-selected injection protocol and scan parameters. The model includes models of organs and vessels using differential equations to describe mass transport of contrast agent through the cardiovascular system. The technique may also predict optimum injection protocol for contrast agent as well as determining an optimum scan interval when enhancement levels are predicted to exceed a threshold level for a time period greater than the scan duration. Further the technique can be used for monitoring a region of interest in the patient different from the region to be scanned after injection to calibrate the mathematical model and more accurately predict enhancement levels in the tissue to be scanned and calculate the optimum scan parameters.
In all of these techniques, the images and test results are indicators of current patient anatomic features and conditions, but are not indicative of the expected results on patient anatomic features and physiologic function from medical intervention. The physician must conceptualize the integration of the patient's anatomic structure and the physiologic function and must assess the efficacy of the alternatives and then conceptualize the expected results of medical intervention. As medical intervention can range from drug therapy to cardiovascular devices to endovascular stents and bypass grafts considering the alternative interventions and the probable effect on each patient is a monumental task. In addition, the physician must also be able to assess the probable outcome of intervention on all of the patient's physiologic states, stresses and environment.
At present, physicians are expected to be able to predict changes in human physiologic function that will occur after medical intervention, i.e. bypass surgery, solely from the experience base of the past and limited data about the present. Human physiology is far too complex for these predictions to be relevant without more sophisticated analytical and computational tools.
The present invention provides the tools for the physician to rapidly integrate the patient's anatomic data and physiologic function in a single model to predict the outcome of various types of medical interventions and to select the intervention most likely to be successful under a number of different physiologic states, stresses and environments. Further this invention allows the physician and others to predict the impact of various physiologic states, stresses and environments on anatomic structures and physiologic functions of patients. And still further this invention provides for the generation of data useful in disease research.